The ServiceWorkerContainer interface of the ServiceWorker API provides an object representing the service worker as an overall unit in the network ecosystem, including facilities to register, unregister and update service workers, and access the state of service workers and their registrations.

Properties

Returns a ServiceWorker object if its state is activated (the same object returned by ServiceWorkerRegistration.active). This property returns null during a force-refresh request (Shift + refresh) or if there is no active worker.

explicitly starts the flow of messages being dispatched from a service worker to pages under its control (e.g. sent via Client.postMessage()). This can be used to react to sent messages earlier, even before that page's content has finished loading.

Examples

The example below first checks to see if the browser supports service workers. If supported, the code registers the service worker and determines if the page is actively controlled by the service worker. If it isn't, it prompts the user to reload the page so the service worker can take control. The code also reports any registration failures.

if ('serviceWorker' in navigator) {
// Register a service worker hosted at the root of the
// site using the default scope.
navigator.serviceWorker.register('/sw.js').then(function(registration) {
console.log('Service worker registration succeeded:', registration);
// At this point, you can optionally do something
// with registration. See https://developer.mozilla.org/en-US/docs/Web/API/ServiceWorkerRegistration
}).catch(function(error) {
console.log('Service worker registration failed:', error);
});
// Independent of the registration, let's also display
// information about whether the current page is controlled
// by an existing service worker, and when that
// controller changes.
// First, do a one-off check if there's currently a
// service worker in control.
if (navigator.serviceWorker.controller) {
console.log('This page is currently controlled by:', navigator.serviceWorker.controller);
}
// Then, register a handler to detect when a new or
// updated service worker takes control.
navigator.serviceWorker.oncontrollerchange = function() {
console.log('This page is now controlled by:', navigator.serviceWorker.controller);
};
} else {
console.log('Service workers are not supported.');
}